1. Field of Invention
The present invention relates to an electro-optical device using electro-optical elements whose brightness is controlled by current, a method of driving the electro-optical device, and an electronic apparatus, and more particularly, to the impulse driving of electro-optical elements.
2. Description of Related Art
Related art methods to enhance the image quality of a hold type display include enhancement in the display characteristics of moving images. In the hold type display, images are continuously displayed during a period of one frame. Display using liquid crystal or organic electronic luminescence (EL) belongs to the hold type display. In the hold type display, data written in a capacitor in a pixel is stored until the data is written again after the lapse of one frame. Thus, the hold type display continuously emits light while the data is stored. For this reason, compared with an impulse type display (for example, a cathode ray tube (CRT)) that temporarily emits light in one frame, afterimages are viewed particularly when moving images are displayed. Therefore, the displayed moving images are not clear. In order to address the problem, a technique referred to as blinking, in which a black image is inserted at predetermined intervals in a process of displaying the moving images, has been suggested in the related art.
For example, a technology that performs blinking by providing switches in voltage lines for supplying predetermined voltages to pixels and controlling the light-emitting time of the organic EL elements using the switches is disclosed in Japanese Unexamined Patent Application Publication No. 2000-347622. Specifically, one frame is divided into a plurality of sub-frames. Data is written for every sub-frame.
The light-emitting period of time of the organic EL elements are set as some periods of time of the sub-frames. The organic EL elements are switched on only during the light-emitting periods of time. Therefore, since the predetermined voltages are supplied to the pixels via the voltage lines during the light-emitting periods of time, the organic EL elements emit light. However, during the other periods of time, the supply of voltages to the pixels is stopped. Thus, the organic EL elements do not emit light (black display). Accordingly, during one sub-field period of time, that is, during a period of time from the moment a certain scanning line is selected, to the moment the scanning line is selected again, each of luminescence and non-luminescence is performed once.
In Japanese Patent Application No. 2002-291145 that is a prior application by the applicant, a technology of applying a forward bias and a reverse bias to the organic EL elements by variably controlling the set voltages of voltage supply lines is disclosed. During the period of time from the moment a certain scanning line is selected to the moment the scanning line is selected again, each of the forward bias and the reverse bias is applied once to the organic EL elements. Therefore, it is possible to suppress the influences due to the difference in the threshold voltages of driving transistors and to reduce the number of transistors that constitute the pixel circuit.